1. Field of the Described Subject Matter
This invention relates generally to integrated circuits, and, more particularly, to compact metal connect and/or disconnect structures that are formed in integrated circuits.
2. Description of the Related Art
Modern semiconductor devices typically include millions of transistors that are interconnected to form the functional elements of the semiconductor device. These simple building blocks can be used to form increasingly sophisticated devices such as central processing units (CPUs), graphical processing units (GPUs), accelerated processing units (APUs), and the like. Although very sophisticated automated design techniques are used to create the layouts that are used to fabricate integrated circuits on semiconductor devices, the immense complexity of these designs almost inevitably leads to unexpected operational behaviors in actual fabricated devices. Consequently, the fabrication process is often an iterative process requiring changes to portions of the semiconductor device that are performed by re-spinning one or more layers. For example, clock trees may need to be fine-tuned, data paths may need to be changed, and logic cells may need to be modified to implement different logical functions.
Re-spinning requires changing one or more layers that include the circuits to be modified, re-forming the circuits according to a new or modified layout or design, and then re-forming all of the overlying layers. Re-spinning is therefore a costly process both in terms of money and in terms of scheduling. The costs associated with re-spinning typically increase in proportion to the number of layers that need to be changed and then re-formed according to the modified layout. For example, conventional integrated circuit designs include several metal layers that are used to form the electrically conductive interconnects that convey electric signals between functional elements such as transistors or other logical units in the integrated circuit. Re-spinning lower-level metal layers is typically significantly more expensive than re-spinning higher-level metal layers, at least in part because lower layers tend to be more complex and re-spinning a lower-level metal layer requires re-forming the layers above the lower-level metal layer.